Want to create your own marker based augmented reality (AR) experience? The first rule for a successful project is to start with an AR marker in mind. While tech enthusiasts often get blown away by the various AR features, the marker image is not secondary to the experience. It is fundamental. An AR marker has quite a few tasks to accomplish. It has to capture your audience’s attention, entice them to pick up their mobiles and scan the image, and finally, only a quality marker will let your AR experience come to life.
What is an augmented reality marker?
An augmented reality marker is an image or an object that can be recognized by an AR-enabled mobile app and is used to trigger augmented reality features. When it comes to DIY projects, markers should primarily be placed on flat surfaces as bumpy, irregular or rounded surfaces deform marker images. If a trigger photo looks different depending on the angle you view it from, your AR experience won’t work. The computer vision algorithm will consider all angles to be an additional marker and only be able to pair the AR content with one of the angles.
A self-service AR creator can be used to combine a marker image with the desired AR content. The audience needs to download a compatible mobile app to scan the marker image. The software then recognizes the image and pairs it with the previously prepared AR content, displaying it on the device’s display in real-time.
While there are a multitude of other tech options for creating augmented reality experiences, marker-based AR is easily the most accessible technology on the market. Firstly, it allows people with diverse IT backgrounds, including little to no tech skills, to breathe life into static visuals. Secondly, the audience of the AR experience only needs a smartphone to retrieve the AR content. The number of mobile phone users worldwide today surpasses three billion spanning all ages, and the market still has high growth potential in many countries (Statista, 2021).
But first, computer vision & AR
In general, computer vision that reads AR markers doesn’t see an image in a traditional sense for its colors or contents but has a technical take on it—tracking feature points. And the more feature points an image has, the better and more stable the AR content that goes on top of it will look. More feature points will guide the computer vision to recognize the marker image and speed up the retrieval process considerably.
You can ensure that a marker has enough feature points by creating designs rich in detail and contrast, including unique patterns. Below is an example of how computer vision perceives a photo. One is lacking the critical prerequisites, while the second one is rich in detail and contrast. Both images can be AR markers, but the first option may reduce the quality and retrieval rates of your AR experiences.
How to choose or create AR marker designs?
The most important rule here is choosing a unique photo from your collection or creating a design from scratch. The risk of using stock photos is that someone else may also pick the same picture. This will distort both your and their AR experience as the software will recognize the image but will not differentiate the content that has to be retrieved.
When designing your marker image, here are other things to take into account:
- Using graphic elements repeatedly will make the marker look the same from all angles. If it is confusing to the human eye, it will be even more consuming for computer vision to detect which direction the marker is placed and retrieve it. Choose irregular shapes and photos that look different from all angles, so the computer vision knows if it is upside down per se.
- Do not use logos as marker images. As tempting as this may seem, a logo may appear in multiple materials in different contexts. If the logo is a marker, it will confuse computer vision. The same goes for the Overly logo. It may be present in other designs, so do not include it in the marker. This will ensure that the right content comes to life when your target is scanned. However, it is good to place your AR provider’s logo within the instructions so people can quickly see what app has to be downloaded.
- Similarly to logos, avoid using the same images or symbols within your design. You can keep your design style aligned while ensuring all elements are unique. For the computer vision algorithm to recognize a marker image, it needs to recognize just around 70 per cent of the marker’s feature points. If key symbols are replicated, and only some elements differ, it will be impossible for the algorithm to differentiate your designs and retrieve the correct content.
- The excellent aspect of this feature is that if an image gets distorted by reflections or light once printed and placed in the desired location, as long as the computer vision can detect most of the feature points, your AR experience will still get retrieved.
- Computer vision doesn’t understand blurred images, so skip on blurry backgrounds whenever possible. Aim for high-resolution images with distinct textures. Remember—blur has no feature points.
- When people scan your AR marker with their mobile device, it must take up at least 50% of their camera screen—no less. So your AR marker could not be a slim line or a tiny dot. Stick to minimal whitespace. You will once more have to think about the marker image and its size once your project goes to print. Read on.
What is the best size for augmented reality markers?
There are a couple of times in the process of creating augmented reality experiences when marker size matters: software upload size and printing size. While the proportions should stay unchanged, size requirements will vary.
- As far as the software upload size goes, the Overly app requires the marker to be high-resolution .jpg or .png pictures. RGB or Grayscale. Up to 2MB. 8 or 24 bit and without transparency.
Printing size is a different question. We do not advise printing anything smaller than a business card because the smaller the marker gets, the harder it is for a mobile camera to focus on it and recognize it.
But the bigger, the better is also not the case. The larger your marker image, the further the person will have to step back to scan the marker to ensure it entirely fits in their mobile camera. Remember the 50% rule. If you think of AR graffiti murals, it is clear that your marker image can be the size of a house, but you have to think about its location thoroughly. There must be enough distance so the audience can step back or get close enough and scan the marker.
One of the most popular AR features in marketing and publishing is complementing magazines, e-books, brochures and other materials with multiple AR markers. We have a whole blog on how print media can reap the benefits of AR in terms of content, but when it comes to target images, here are vital tips:
- Markers that contain too much text are not providing enough distinct imagery to computer vision, making the AR content unstable. If you want to bring a mostly text page alive, feature an in-text graphic element as a marker. This approach is often used by magazines and newspapers when concrete pictures or objects are brought to life within a text page.
- However, in the above scenario, do not use two markers on one page. This ensures a good user experience (UX). When people see that augmented reality content can be retrieved on printed materials, there is a clear tendency to hold a mobile device to get the whole page into the device’s camera. If the camera has two markers in its sight, none of the markers will come alive.
- If possible, split the text from the graphic elements and use the whole page design as a marker page instead of just the image within the page. The user won’t have to struggle to scan a small item. This again goes back to the UX and the way people hold their devices. If a marker image is small, their camera may be too far away to detect a smaller marker. Remember the 50% rule.
What are AR marker printing considerations?
The first and the most important thing is to choose a print material that does not reflect light too much. Go for matte wherever possible.
- If you go for a glossy finish and then put a poster outdoors, the sun may shine right at it at some points during the day, and once the light reflects on it, the image your mobile perceives will be distorted. If you go for a matte finish, you don’t have to think of the placement that much. At all costs, avoid gold and silver when it comes to AR.
- Another thing for the best marker recognition quality is choosing hard print materials. This starts with a cardboard business card, going up to a wooden canvas, billboards, etc. The main thing is to ensure that the material doesn’t get deformed in its environment as it bends, etc. If a marker image gets distorted, it may be impossible to scan. So a key consideration: marker print material must withstand any given conditions.
- Many people love the idea of AR clothes, and there are many fantastic examples out there. When going for a DIY project, remember that clothing can wrinkle up, markers can fade with every wash, and the novelty AR effect may not work in time. Thoroughly consider marker placement. Ensure it is not in a spot that wrinkles or stretches out when clothes are worn and choose the washing regimen wisely.
Can you place augmented reality markers on bottles?
In theory, marker images can be recognized on curved surfaces, but it is best to opt for a flat surface for a DIY project. If you opt to place a marker image on a bottle or a can, it will most likely be deformed, and while it will get recognized by mobile apps, the content will not be as stable.
If it is a must for your project, you may have to skip the DIY efforts and require additional technical support from an agency that will deliver your AR experience. Below is a quick glance at an AR project for a wine bottle we delivered to our clients for Christmas.
If you want to learn more about creating marker-based augmented reality experiences, you can read a blog from Overly’s CTO, Gatis Zvejnieks. Any questions, get in touch or leave a comment below.